1. Field of the Invention
The present invention relates to a charged particle beam exposure system used, for example, in a lithographic method, and a beam manipulating arrangement for manipulating a plurality of charged particle beams.
2. Brief Description of Related Art
Lithographic processes are commonly used in the manufacture of miniaturized structures, such as semiconductor elements, integrated circuits, liquid crystal elements, micro-patterned members and micro-mechanical components.
A lithographic process comprises a plurality of lithographic steps in which patterns or structures to be formed on a substrate are imaged onto the substrate to expose a radiation sensitive layer provided on the substrate. The radiation sensitive layer, which is commonly referred to as a resist, may be exposed by optical radiation, such as visible or ultraviolet light, or by charged particles, such as ions or electrons. In the imaging of patterns using charged particles, a conventional method uses a plurality of charged particle beams or beamlets for writing the pattern onto the resist, wherein the beams or beamlets can be selectively switched on and off while the substrate carrying the resist is moved relative to the array of switchable beams.
The switchable beams are controlled by a deflector plate having a plurality of apertures traversed by the beams. Each aperture has a deflector associated therewith for selectively deflecting the beam traversing the aperture by a sufficient angle such that the beam will not reach the substrate carrying the resist. Such type of multi-aperture plate is also referred to as a blanking aperture plate (BAA) in the art. Background information on charged particle beam exposure systems using a plurality of charged particle beams controlled by a blanking aperture array may be obtained from US 2003/0025088 A1, the contents of which are incorporated herein by reference.
In the conventional system using a multi-aperture plate for controlling the charged particle beams, the plurality of beams is formed by generating a beam incident on the multi-aperture plate and extending across a plurality of apertures on the plate. A portion of the charged particles incident on the plate may traverse the plate through the apertures such that an array of charged particle beams is formed downstream of the multi-aperture plate. The other portion of charged particle beams is intercepted by the plate. Further, the multi-aperture plate carries the deflectors associated with each of the apertures, and the multi-aperture plate carries also the circuitry necessary for controlling switching states of the deflectors.
It has been found that the conventional system of exposing a pattern using a plurality of controlled charged particle beams may have an insufficient performance in some applications.